[V2] Need help writing toolset that generates CPP files

From: Christopher Currie (Christopher_at_[hidden])
Date: 2003-10-31 16:16:04

I'm trying to build a toolset that implements the following scenario:

exe xmlapp : main.cpp [ xml-cpp Person.cpp Name.cpp : schema.xml ] ;

I'm writing for a tool called XML ObjectLink. This tool creates a set of 
C++ source files to implement parsing and generating elements of an 
XML schema. Roughly, one source and one header are created for each 
top-level element and named type in the schema.

The trouble of course, is that there is no way to deduce the name of 
these source file from the name of the schema file. So I needed to write 
a rule that took the expected names as arguments, putting some burden 
upon the user to give the correct generated names.

I've been pretty successful so far, I've almost got it working. Here is 
my current implementation:

# objectlink.jam

import type ;
import "class" : new ;
import generators ;
import targets ;

type.register XSD : xsd ;

rule xsd-cpp ( targets + : source : requirements * : default-build *
: usage-requirements * )
{
local project = [ CALLER_MODULE ] ;

targets = $(targets:B) ;

for local name in $(targets)
{
targets.create-typed-target CPP
: $(project) : $(name) : $(source) : $(requirements)
: $(default-build) : $(usage-requirements) ;
}

return $(targets) ;
}
IMPORT $(__name__) : xsd-cpp : : xsd-cpp ;

generators.register-standard objectlink.schema-compile : XSD : CPP ;

actions schema-compile
{
xsd2cpp -outdir "$(<:D)" "$(>)" ;
}

So far, so good. The only problem is that the system now runs the 
schema-compile action once for each generated CPP file, even though the 
tool will create them all at the same time.

Obviously I needed a way to specify that the generator was going to 
create multiple targets, and so I tried adding:

generators.register [
new generator objectlink.schema-compile
: XSD : CPP($(targets).cpp)
] ;

into my rule, just before the return, and removing the standard 
generator below. This broke the build, because somewhere my CPP targets 
are getting defined twice. My build now gives the errors below.

I figure that the generator is defining new virtual-targets with the 
same file-target name, because my generator output is fixed. So what I 
probably need to do is not create the typed-targets, and return the 
virtual-targets from the generator. Trouble is, I can't figure out how 
to get those target id's out of the generator.

Am I on the right track? Or is there another way to solve this dilemma?

Thanks,
Christopher

$ bjam
/home/ccurrie/src/boost/tools/build/v2/build/virtual-target.jam:758: in 
virtual-target.register-actual-name from module virtual-target
error: Duplicate name of actual target: <./sun/debug>Person.cpp
previous virtual target { 
objectlink%objectlink.schema-compile-Person.CPP { test.XSD } }
another virtual target { objectlink%objectlink.schema-compile-Person.CPP 
{ test.XSD } }
/home/ccurrie/src/boost/tools/build/v2/build/virtual-target.jam:176: in 
actualize-no-scanner from module object(file-target)@3
/home/ccurrie/src/boost/tools/build/v2/build/virtual-target.jam:110: in 
object(file-target)@3.actualize from module object(file-target)@3
/home/ccurrie/src/boost/tools/build/v2/build/virtual-target.jam:568: in 
object(action)@1.actualize from module object(action)@1
/home/ccurrie/src/boost/tools/build/v2/build/virtual-target.jam:279: in 
actualize-action from module object(file-target)@2
/home/ccurrie/src/boost/tools/build/v2/build/virtual-target.jam:184: in 
actualize-no-scanner from module object(file-target)@2
/home/ccurrie/src/boost/tools/build/v2/build/virtual-target.jam:110: in 
object(file-target)@2.actualize from module object(file-target)@2
/home/ccurrie/src/boost/tools/build/v2/build-system.jam:168: in load 
from module build-system
/home/ccurrie/src/boost/tools/build/v2/kernel/modules.jam:259: in import 
from module modules
/home/ccurrie/src/boost/tools/build/v2/kernel/bootstrap.jam:120: in 
boost-build from module
/home/ccurrie/src/xml/boost-build.jam:1: in module scope from module